The Micius experiment deployed
quantum communication protocols via discrete variable (DV) technology where the quantum information was encoded in the polarization state of single photons [1]}, [2]}.
Alternatively, continuous variables (CV) quantum information, where the information is encoded in the quadratures of the electromagnetic field of optical states, is widely touted as perhaps a more promising candidate to transfer quantum information [3]}, [4]}. This is largely
due to the relative technical simplicity (and maturity) of the CV-enabled devices required to send, receive, and measure quantum signals, robustness against background noise, and the potential of the enlarged Hilbert space associated with CV systems to lead to enhanced communication throughput in practical settings.In theory both DV and CV communication deliver the same throughput, and the reality is both systems have their pros and cons. However, there certainly is a school-of-thought that in many pragmatic systems, the higher-dimensional encoding space directly available to CV systems will lead to enhanced outcomes. A detailed discussion of the pros and cons of both DV and CV systems is given in [5]}.
For these reasons, there is great interest in pursuing designs of CV-enabled quantum satellites, with many recent studies focusing on the more feasible satellite-to-ground (downlink) transmission of quantum signals, largely with a view to enable CV-QKD [6]}, [7]}. As yet, there has not been any experimental realizations of satellite-based CV quantum communications. In this work, we turn to a hitherto overlooked type of satellite-based CV quantum communications, namely, the use of CV quantum downlink communications as a means to enhance ground-to-satellite (uplink) quantum communications with a LEO satellite.
